The invention relates to a device for securing a support structure, such as a stand, frame, profile part, or solar module carrier on a flat roof, provided with an insulating layer covered by a sealing strip, comprising an upper connection element for the support structure, a spacer member that can be passed through an opening in the sealing strip and the insulating layer to support the upper connection element on a roof sub-structure, and at least one anchor part to anchor the spacer member on the roof sub-structure.
One fastening device is known from the document DE 20 2004 005 224 U1, which is here called an assembly system, which is particularly embodied to form an upper connection element as a profile adapter, which guides a profile carrier in a displaceable fashion. The assembly system comprises an assembly foot, which is anchored perpendicularly in reference to the longitudinal carrier on the roof sub-structure using two anchor fasteners. In order to support the upper connection element on the roof sub-structure two spacer parts embodied cup-shaped are used, which contact the supporting roof sub-structure with a bottom. Two holes must be produced in the insulating layer for the two spacer parts, which additionally must be aligned with bores for an anchor fasteners in the assembly foot. The assembly of each assembly foot is therefore complicated. Furthermore, the tipping stability of the assembly foot, with its base area being a narrow rectangle, is respectively low. Longitudinal carriers are necessary to compensate the low tipping stability, which connect the assembly feet arranged successively. If a punctual fastening of a support structure is necessary instead of longitudinal carriers, thus no longitudinal carrier is present, the tipping stability cannot be improved. Finally, the assembly system of prior art is designed for certain thicknesses of insulation materials. In case of different thicknesses of insulation materials differently embodied spacer parts must be used. This assembly system of prior art is not suitable for the assembly of solar modules on already existing flat roofs, because the insulation layer must be passed through the two pressure plates, thus can only be applied subsequently when the cup-shaped spacer parts with the lower pressure plate already rest on the roof sub-structure.
A similar fastening device known from the document DE 20 2006 007 948 U1 forms a support system to introduce loads via a support structure into a carrying roof sub-structure with a trapezoid sheet metal, which rests on the binders of the roof sub-structure. A foot element at the lower end of the spacer part is provided to connect to the roof sub-structure, which stands on the recessed beads of the trapezoid sheet metal and can be fastened on the binders. The spacer part extends between the foot element and the connection element and is connected to these two elements. The foot element overlaps the raised bead of the trapezoid sheet metal in order to rest directly on the roof sub-structure. Accordingly it is so wide that it cannot be guided through the sealing strip and the insulation layer for assembling the fastening device, but must be assembled on the trapezoid sheet metal before the sealing strip and the insulation layer are applied on the trapezoid sheet metal. This aggravates the subsequent application e.g., of solar modules for photovoltaic and collector installations on already existing flat roofs, which are already provided with a sealing strip and an insulation layer. In order to allow connecting the fastening device of prior art with the roof sub-structure first at least the sealing strip must be removed and the insulation layer be opened so that the foot element can be placed on two adjacent recessed beads precisely above the binder and then screwed via two screws to the binder. Only thereafter the sealing strip can be reapplied. Finally, the spacer part can project far beyond the sealing strip so that the sealing strip can be pulled up at the spacer part for sealing purposes and connected thereto in a sealing fashion.
In another, similar fastening device known from the document EP 1 619 727 A2 the spacer parts are embodied as anchor feet, each comprising a plate as a foot part which can be fixed via a screw connection, by which they are directly screwed onto the supportive sub-structure. This fastening device is even less suitable for a subsequent assembly on an existing flat roof, because the anchor feet penetrate not only the insulation layer but also the trapezoid sheet metal.
In a roof fastening device of prior art known from the document DE 10 2007 053 556 A1 a penetration element is provided, which comprises a threaded rod, which is welded to a cover element. Such a roof fastening device can be fastened on an existing flat roof subsequently because for the penetration element only one bore hole must be created, which penetrates the sealing strip and the insulating layer. The threaded rod can be guided through a trapezoid sheet metal and directly anchored in the roof sub-structure. In order to improve the sealing the cover plate is sealed at the sealing strip. This roof fastening device can therefore be used on an existing flat roof, however the carrying capacity and the stability with regards to tipping and torsion are relatively limited by the use of a threaded rod as the penetration element.
A fastening device of the type mentioned at the outset is known from the document WO 2007/093421 A2. In this fastening device the spacer device is formed by three units. The roof skin must be cut open, so that these three units can be inserted. One of the units carries a sealing collar, which subsequently must be glued or welded to the remaining roof skin. The units comprise two large-area support plates, between which a threaded rod is screwed in as a spacer element in threaded sections of two tube sections, which are welded to the support plates. Due to the large-area support plates the roof skin including the insulation layer must be cut open over a large area. As already mentioned, the use of a threaded rod as a spacer element is problematic with regards to stability concerning tipping and torsion. Finally, in this fastening device the threaded rod is the only variable part of an assembly group formed from three units, which must be warehoused in various lengths.
From the document FR 2 831 576 A1 a block is known for fastening a support rod of a banister or a barrier. The fastening block serves to fasten a holding rod or a rod carrying a safety barrier on a concrete plate, which may represent a balcony or terrace plate. This plate is coated with a sealing and insulating layer, with at least a portion being pulled upwards at the block. The block embodied like a bushing is screwed to a base showing a greater diameter. The sealing and insulating layer can be pulled upwards at the block after the assembly of said block resulting in the type of assembly problems described above.